A combined EPR and MD simulation study of a nitroxyl spin label with restricted internal mobility sensitive to protein dynamics.

•Rn and MTSL (R1) protein spin labels by EPR and fully atomistic MD simulations.•Comparative study between the motions of Rn and R1 attached to Myoglobin.•Evidence for intrinsic low rotameric mobility of Rn spin label.•Uncovering the potential for using Rn as a sensitive reporter of protein dynamics.